Strange Orbits

Like toy cars chasing each other on a looped racetrack, three stars can, in principle, trace out a figure-eight orbit in space. This surprising pattern of motion arises from the force of gravity acting on three bodies of equal mass. The movements are timed so that each body in turn passes between the other two. Moreover, such coordinated movements aren't the only intricate maneuvers possible when several bodies attract one another gravitationally.

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